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11.
A. Ricci M. Incerti E. Rolli P. Vicini G. Morini M. Comini C. Branca 《Plant Growth Regulation》2006,50(2-3):201-209
The present research investigates the biological profile of eight symmetrical diheteroarylureas and phenylheteroarylureas, testing their hypothetical cytokinin-like activity and rooting activity. Cytokinin-like activity was assayed by the betacyanin (so-called amaranthin) accumulation test and by the tomato regeneration test. The rooting activity was assessed using the mung bean rooting test, the apple stem slice test and the rooting of apple microcuttings. Three compounds, 1,3-di(pyrazin-2-yl)urea (3a), 1,3-di(benzo[d]oxazol-5-yl)urea (3b) and 1,3-di(benzo[d]oxazol-6-yl)urea (3c), enhanced adventitious root formation in apple stem slice test, but only 3b and 3c were active in the mung bean rooting test. Compound 3b, that showed the best rooting activity, was also able to enhance the adventitious root formation in apple microcuttings. None of the compounds showed cytokinin-like activity. 相似文献
12.
Sexual and seasonal differences in the frequency of beak marks on the wings of two Lethe butterflies
Jun-Ya Ide 《Ecological Research》2006,21(3):453-459
To assess bird predation pressure on butterflies, I investigated beak marks on the wings of two Lethe butterflies for 3 years in secondary temperate forests. If bird predation had significant effects on average longevity of
butterflies, and if the number of specimens preyed upon was proportionate to the number of beak-marked specimens, the beak
mark frequency would be negatively correlated with average longevity of a butterfly. Bird predation pressure is generally
thought to influence average longevity of butterflies. Therefore, if there is a negative correlation between beak mark frequency
and average longevity, bird predation pressure would be reflected in beak mark frequency. Beak mark frequency was negatively
correlated with longevity in Lethe diana (Butler), the more abundant of the two species; thus, the beak mark frequency was considered to be a suitable index of bird
predation pressure on the butterflies investigated in this study. In both Lethe species, beak mark frequency was higher in females than in males. Because female butterflies have a relatively smaller thorax
and flight muscles and a larger abdomen that contains eggs, they are presumably weaker or less agile fliers than males, and
are probably attacked more easily by birds. In autumn, butterflies were heavily attacked by birds irrespective of sex and
species. Because the numbers of lepidopteran larvae, which are the preferred prey of many birds, decreased in autumn, birds
were thought to shift their diets to alternative prey such as adult butterflies. 相似文献
13.
Synthesis and characterization of 5,5′-dibromo-2,2′-dipyridyl disulfide and some of its derivatives under mild reaction conditions is described. A series of some novel synthetically important symmetrical/unsymmetrical bromo substituted pyridyl alkyl/aryl sulfur compounds have been easily synthesized from a variety of alkyl halides, using NaBH4 in moderate to good yields. The important features of this protocol are strong base-free, operational simplicity, short reaction time and high yield. The synthesized compounds are characterized with the help of elemental analysis, IR, 1H NMR, 13C NMR and mass spectral data (in representative cases). X-ray crystal structure analysis of 5,5′-dibromo-2,2′-dipyridyl disulfide (1) and bis(5-bromopyridine-2-ylthio) methane (2a) have been carried out to establish their molecular structure. Compound (1) and (2a) are monoclinic and crystallizes into P21/n and C2/c space group, respectively. 相似文献
14.
A series of oxovanadium(IV) symmetrical tetradentate Schiff base complexes have been isolated from the reaction of VOSO4 with Schiff bases obtained from the condensation of 2-hydroxybenzophenone or 2-hydroxy-5-chlorosalicylaldehyde with various aliphatic diamines. The compounds were characterized by elemental analyses, 1H NMR, infrared, electron paramagnetic resonance, electronic spectral, cyclic voltammetry and room temperature magnetic susceptibility measurements. The solution EPR spectra are consistent with square pyramidal complexes with C4v symmetry. The IR spectra confirmed that the complexes are all monomeric except for [VO(Clsal)2tn] which polymerizes via OV?VO linkages. The electronic spectra indicate a square pyramidal geometry in both non-coordinating and coordinating solvents except for [VO(bp2-pn)] which appears to be octahedral in DMSO. The room temperature magnetic moments of 1.7-1.8 B.M. are normal for V(IV) d1 configuration. Evidence for electrochemical pseudo-reversibility is presented for four of the complexes. In vitro studies revealed that two of the compounds, [VO(bp2-en] and [VO(bp2-tn)MeOH], significantly increased glucose uptake when compared to the basal glucose uptake in transformed and sensitized C1C12 cells, but not at the same level as insulin. 相似文献
15.
PST13-RK (KKKFPWWWPFKKK-NH2) is an improved derivative of tritrpticin adopting a β-turn structure. In order to investigate the effect of dimerization
of PST13-RK on antimicrobial activity and mammalian cell toxicity, we designed and synthesized its Cys- and Lys-linked dimers.
The dimerization of PST13-RK resulted in a 2–4 fold decreased antimicrobial activity against Gram-positive and Gram-negative
bacteria. However, the dimers showed a large increase in mammalian cell toxicity against mouse NIH-3T3, human MDA-MB-361,
and human A549 cells. These results suggested that PST13-RK is active as a monomer to bacterial cells but as an oligomer to
mammalian cells. Since the dimeric PST13-RK is much more effective against the cancer cells than the monomer, it might be
an attractive candidate for anticancer chemotherapeutic drugs. 相似文献
16.
Summary The synthesis of a series of symmetrical disulfides as potential substrates of trypanothione reductase and glutathione reductase was described. The key intermediate in the synthetic approach was the choice of S-tbutylmercapto-L-cysteine (1). The spermidine ring in the native substrate, trypanothione disulfide (TSST), was replaced with 3-dimethyl-aminopropylamine (DMAPA), while the-Glu moiety was replaced by phenylalanyl or tryptophanyl residues. The same modifications in the-Glu moiety of glutathione disulfide (GSSG) were applied. 相似文献
17.
18.
The interpretation of mass spectra (ms) of molecules containing poly-isotopic elements (e.g. Ge, Se, W, Os, Sn, Te, Zn, Yb)
can be difficult due to the occurrence of fragments resulting from isotopomeric composition. MS-clusters located in the range
lower than or equal to M/2 are very difficult to interpret. In this area many perturbations may be observed. The coincidence
of different fragmentation pathways, the existence of multiply charged ions, background levels, etc. can all contribute to
this problem. The present paper reports the application of multi-isotopomeric analysis methods for low-resolution ms. We present
a solution that may be useful for detection of the symmetrical decomposition of a molecule and for elucidation of cluster
ion genesis. The complex character of the cluster does not perturb determination of the contents of the investigated pattern.
In such cases the dominated component is applied in subsequent computations.
相似文献
Andrzej J. GorączkoEmail: |
19.
Lars S. Jermiin Peter G. Foster Dan Graur Roger M. Lowe Ross H. Crozier 《Journal of molecular evolution》1996,42(4):476-480
The most generally applicable procedure for obtaining estimates of the symmetrical, or strand-nonspecific, directional mutation
pressure (μD) on protein-coding DNA sequences is to determine the G+C content at synonymous codon sites (P
syn), and to divide P
syn by twice the arithmetic mean of the G+C content at synonymous codon sites of a large number of randomly generated, synonymously
coding DNA sequences (P
syn). Unfortunately, the original procedure yields biased estimates of P
syn and μD and is computationally expensive. We here present a fast procedure for estimating unbiased μD values. The procedure employs direct calculation of P
syn (≈P
syn) and two normalization procedures, one for P
syn≤P
syn and another for P
syn≥P
syn. The normalization removes a bias sometimes caused by codons specifying arginine, asparagine, isoleucine, and leucine. Consequently,
comparison of protein-coding genes that are translated using different genetic codes is facilitated.
Received: 5 May 1995 / Accepted: 30 November 1995 相似文献
20.
Sree Kanth Sivan Radhika Vangala Vijjulatha Manga 《Bioorganic & medicinal chemistry》2013,21(15):4591-4599
Induced fit molecular docking studies were performed on BMS-806 derivatives reported as small molecule inhibitors of HIV-1 gp120–CD4 binding. Comprehensive study of protein–ligand interactions guided in identification and design of novel symmetrical N,N′-disubstituted urea and thiourea as HIV-1 gp120–CD4 binding inhibitors. These molecules were synthesized in aqueous medium using microwave irradiation. Synthesized molecules were screened for their inhibitory ability by HIV-1 gp120–CD4 capture enzyme-linked immunosorbent assay (ELISA). Designed compounds were found to inhibit HIV-1 gp120–CD4 binding in micromolar (0.013–0.247 μM) concentrations. 相似文献